Patent GB-184141-A (GB)
Title: Improvements in and relating to electric arc welding apparatus
IPC: B23K9/12
Filed: 1922-03-03
Abstract: 184,141. British Thomson - Houston Co., Ltd., (Assignees of Noble, P. 0.). July 27, 1921, [Convention date]. Uniting by fusion.-In an arc-welding apparatus of the type in which a fusible metal electrode is continuously fed towards the work as consumed. the electrode wire is guided from the feedmechanism to the welding-tool or carriage by a flexible insulating guide so that welding may be performed at any point in the vicinity of the apparatus. In the form shown in Fig. 1, in whieh the wire 4 is fed from a spool 13 through straightening rolls 14, 15 by feed rolls 9, which are rotated by gearing from a motor 11, the wire passes to the welding tool 1 through a flexible tube 16. The welding-tool, which is traversed over the work by hand or automatically, is mounted on insulated wheels 3 and contains current-supplying rolls 5. The motor is connected across the welding circuit so that its speed and thus that of the wire-feed is dependent on the voltage across the arc, so as to maintain the length of the arc constant. Apparatus of such type is described in Specifications 139,919, 145,330 and 179,613, [Class 38 (iii), Electric motor control systems &c.]. In a modification a. wheeled welding-tool may be traversed over the work by a stationary motor through a flexible shaft and gearing, the wheels being held magnetically to the work and the welding-current supplied through a winding on the shaft. In another form, the control circuits are arranged as described in Specification 179,613, [Class 38 (iii), Electric motor control systems &c.], so that the feed motor may be reversed to strike the arc, the current being supplied from a generator as described in Specification 159,374, [Class 35, Dynamo-electric generators &c.]. The flexible guide-tube connects the feed-roll frame with a tubular hand-tool, which can thus be manipulated to weld on upper or lower surfaces of work or in corners or inside hollow articles. The push-button switches are also mounted in the hand-tool. In a further form, Fig. 13, the current is supplied from a generator 141 as previously referred to, across the constant voltage brushes 45, 43 of which the fielding winding 149 of the electrode feed motor is connected through a resistance 150. When the contactor 148 is closed by touching the electrode 4 to the work to strike the arc, the motor armature 142 is connected across the welding circuit 146, 147, by way of the switch 151 so as to keep the length of the arc constant. Welding is stopped by moving the tool 145 quickly away from the work. In order to keep the motor in operation when the welding circuit is open, for the purpose of feeding in a new electrode &c., the switch is thrown over to connect the motor armature across the constant voltage brushes. A resistance such as a portion of the resistance 150 is used to provide a slow speed. In a further form, the motor armature is connected across the constant voltage mains so that the rate of feed is constant. The rate of feed is varied by the operator either through adjustable speed gearing, or by adjusting a resistance in the field of the motor or by moving the tool. In this form lengths of wire may be fed intermittently from the spool and welding performed as ordinarily between each feed movement. A hand welding-tool may consist of an insulator tube 68, Fig. 4, provided at one end with a screwed cap 76 having an integral or detachable electrode-delivery nozzle 75 and at the other end with a block 72 and nut 70 engaging wedges 71 for clamping it to the flexible guide tube 69. The stranded conductor 80 for carrying the welding-current may be braided on the guidetube and soldered or otherwise fixed to a pair of brass or copper levers 78 carrying contact rolls 77 of tungsten, which are mounted in self-lubricating bearings. The levers are jointed together as shown at 82 and are pressed together by a spring 83. An insulating washer 84 may be provided between the levers and the cap 76, and air circulating holes 85 provided in the tube to keep the spring cool. In the form shown in Fig. 6, the current conductors 80 are soldered to a block 91' which is connected by screws 92 to the tube 93, and the contact rolls are replaced by a rotatably adjustable curved nozzle 86 which is pressed into contact with the block 91' by a screwed cap 94<1>. 'The hand-grip of the tool may have a caster 97 for steadying purposes. The guide-tube 69 consists of a flexible metal hose 88 which is covered with an insulating sleeve 89 on which the conductor 80 is braided together with the control wires 95. This is covered with a second insulating sleeve 90 surmounted by a metallic armour 91. The conductor may be clamped between a block such as 91<1> but tapered at its rear end and a similarly tapered nut screwed thereon. A steady-rest 99, Fig. 9, may be clamped in desired position on the hand-tool 93 the stem 101 of which has an adjustable sleeve 102 with caster 104. The upper end of the electrode guide-tube 69 is secured in a block 112, Fig. 10, fixed by screws to a member 109, which in turn is fixed to a hollow member 106 screwed in the frame 105. The upper end of the conductor 80 is soldered to the block and the welding-current lead connected to the clamp 115. Control wires 113 may be led through slots 114 in the member 109. In welding flues to Hue sheets, the tool is secured to a block 122, Fig. 11, rotatably mounted on a member 123, which is clamped to the flue by insulating blocks 124 radially moved by a screw-adjusted tapered mandrel 128. The guide tube 69 is carried by a ball-and-socket joint 119 in the frame 120 which is pivoted at 121 to the block 122, the inclination being adjusted by stop screws 132, 133. The block 122 may be rotated during welding either by hand or by a spring or other motor. The member 123 has a heat-insulating sleeve 134. In a modification, the pivoted frame has a rearwardly extending arm which is held by a spring in contact with a cam secured on the member 123 so that the electrode may be oscillated across the joint during rotation of the block 122. The Specification as open to inspection under Sect. 91 (3) (a) describes a. modification in which the motor is mounted on a wheeled welding carriage, the contact rolls in this case serving also as the feed rolls. The flexible tube is secured to the tool by an insulated bracket and the rolls are mounted in insulated bearings so as to avoid the necessity for insulating the wheel bearings. This subject-matter does not appear in the Specification as accepted.